镁基储氢合金氢化物Mg_2NiH_4的制备及性能研究

Preparation and property of magnesium based hydrogen storage alloy hydride Mg_2NiH_4

以不经压制的Mg、Ni混合粉末为原料,利用氢化燃烧合成法在合成温度850 K和1.8 MPa初始合成氢压下制备了镁基储氢合金氢化物Mg2NiH4,并利用XRD及PCT仪分析了其物相组成和储氢性能。研究表明,产物由单一物相Mg2NiH4组成,无未反应的Ni和不完全氢化的Mg2NiH0.3;相对于传统熔炼法制备的Mg2Ni,氢化燃烧合成产物具有更高的氢化活性,在没有任何活化处理的前提下,第一次吸氢就能以很快的速度达到饱和吸氢量,同时在任何吸氢温度下均具有较好的吸氢动力学性能,且随温度的降低,最大吸氢量降低幅度较小,平台压和吸放氢温度的关系为:lgP(0.1 MPa)=-3 187.6/T+6.362 4(吸氢),lgP(0.1 MPa)=-3 468.4/T+6.694 3(放氢)。

Magnesium based hydrogen storage alloy hydride Mg2NiH4 was prepared by hydriding combustion synthesis （HCS） at the condition of synthesis temperature of 850 K and initial hydrogen pressure of 1.8 MPa, using the uncompressed Mg - Ni mixed powder directly. Phase composition and hydrogen storage property were also investigated by means of X-ray diffraction and pressure composition isotherm. The results indicated that the composition was pure Mg2NiH4. The hydriding activity was very high so that it absorbed the saturated a- mount of hydrogen without any activation process. The kinetic property of hydrogen storage was better than the product of conventional ingot metallurgy at every hydriding temperature, and the amount of hydrogen storage decreased slowly with the decrease of temperature. The relationships between the equilibrium plateau pressure and the temperature were lgP （0. 1 MPa） = - 3 187. 6/T ＋ 6. 362 4 for hydriding and lgP （0. 1 MPa） = - 3 468.4/T ＋ 6. 6943 for dehydriding.